A Study of the Effect of Thallium Acetate Upon the Growth of the Flexner—Jobling Tumor in Albino Rats

Abstract

Introduction

Thallium acetate has been used for some time therapeutically as an epilatory drug in fungus infections of the scalp. The usual therapeutic dose in children has been 8 mg. of thallium acetate per kilogram of body weight. There has been a considerable volume of literature (1) discussing the epilatory action of thallium, and in our own laboratory certain studies involving the action of thallium on hair in albino rats have been under investigation (1,2). Percival (3) believes that thallium inhibits young, actively proliferating epithelial cells of the hair follicle and bulb. This possibility suggested to us that thallium might inhibit the growth of other young, actively proliferating epithelial cells, as those of cancer.

The work of Blair Bell (4) with colloidal lead in cancer in man also suggested that thallium, which resembles lead in certain physical and chemical properties (1), might have some inhibitory or toxic effect upon cancer cells. For this reason a preliminary experiment was undertaken to determine whether thallium would have any effect on tumors in animals.

The Flexner-Jobling tumor was selected and transplanted in a number of young rats. As a preliminary trial, six rats with tumors about the size of a small pea were given an intraperitoneal injection of thallium acetate in the dosage of 12 mg. per kilogram of body weight. Six rats with tumors of about the same size were reserved as controls. It so happened that in all six of the rats which received thallium there was a rapid recession of the tumor. The tumor continued to grow in four of the control rats; in the other two control animals the tumor receded. We felt warranted in proceeding with the following experiments: